A high-strength steel inner surface defect detection device and method

Abstract

This application discloses a device and method for detecting defects on the inner surface of high-strength steel, relating to the field of automatic detection. The device includes: a main control system, a composite electromagnetic detection module, and a lift-off adjustment mechanism; the main control system and the lift-off adjustment mechanism are electrically connected; the lift-off adjustment mechanism is mechanically connected to the composite electromagnetic detection module; in the composite electromagnetic detection module, both the magnetic flux leakage channel structure and the permeability channel structure are electrically connected to the mode switching and control unit, and the magnetic flux leakage channel structure and the permeability channel structure share a magnetizer; the lift-off adjustment mechanism adjusts the lift-off height of the magnetizer; the main control system parses the detection command and determines the detection mode based on the lift-off height; the mode switching and control unit activates the magnetic flux leakage channel structure or the permeability channel structure for detection based on the detection mode to obtain a detection signal. This application can maintain high sensitivity and high reliability in detecting defects on the inner surface of high-strength steel containers over a wider lift-off range, significantly improving the adaptability and comprehensive evaluation capability of coating-free grinding detection.

Description

Technical Field

[0001] This application relates to the field of automatic inspection, and in particular to a device and method for detecting defects on the inner surface of high-strength steel. Background Technology

[0002] High-strength steel storage containers (such as spherical tanks) are key equipment in the petrochemical and energy storage fields. Their inner surfaces are subjected to high pressure and corrosive media for extended periods, making them prone to fatigue cracks. Non-destructive testing of internal surface cracks is crucial for ensuring the safe operation of these containers. Magnetic flux leakage testing has become one of the most widely used offline testing technologies for steel plates due to its advantages such as not requiring surface coating grinding, fast testing speed, and low surface requirements.

[0003] However, with the increasing size of containers and the growing demands for testing efficiency and safety, the need for rapid testing without opening the can or cleaning the surface coating is becoming increasingly urgent. High-strength steel spherical tanks typically have thick walls (e.g., over 20 mm), and the magnetic leakage field generated by cracks on the inner surface is extremely weak after penetrating the thick-walled ferromagnetic material. Simultaneously, the container surface is often covered with an anti-corrosion coating, requiring the detection probes (magnetizer and sensor) to be kept at a certain lifting height to avoid scratching the coating or being affected by surface unevenness. In the prior art, Chinese patent application CN118131795A discloses an adaptive lifting control method for a magnetic leakage detection robot based on inertial navigation and hydraulic lifting. This method uses a detection module to collect magnetic leakage signals in real time and determine whether a saturation magnetization state has been reached, thereby adjusting the distance between the detection module and the steel plate. While this method achieves adaptive adjustment of the lifting, it still has the following limitations: 1. The contradiction between lift-off height and detection sensitivity: This scheme relies on the traditional magnetic flux leakage (MFL) detection principle, and its detection performance is heavily dependent on small lift-off distances, with effective detection lift-off generally not exceeding 10mm. In actual working conditions (such as scenarios with thick deposits on the steel plate surface, large welds, and simultaneous evaluation of steel plate thickness and material properties), when a greater obstacle-crossing height is required, the lift-off distance needs to be further increased (e.g., greater than 15mm to overcome thicker deposits or larger welds). At this point, the MFL signal strength will rapidly decay exponentially to noise levels, causing a sharp deterioration in the signal-to-noise ratio, leading to an increased false negative rate for small back-side defects and detection failure. Although optimizing the magnetizer can improve performance at certain lift-off distances, due to physical laws, this improvement has an upper limit. Single MFL detection still faces the fundamental bottleneck of weak signal and insufficient signal-to-noise ratio.

[0004] 2. Limited detection methods and insufficient information dimensions: This solution only uses magnetic flux leakage detection technology, which cannot obtain information on changes in the magnetic properties of steel plate materials, and has limited ability to identify defects such as deep corrosion and stress concentration.

[0005] 3. Shortcomings of a simple parallel approach using multiple technologies: Although multiple technologies are integrated, each module operates independently, increasing the system's size, weight, cost, and complexity. In particular, there is a lack of physical and signal-level coordination between the magnetic flux leakage module and other modules (such as ultrasound). For electromagnetic defect detection, the characteristic that the same magnetization field can simultaneously generate both leakage magnetic field and permeability perturbation—two related physical effects—is not fully utilized, resulting in wasted hardware resources and potential information loss.

[0006] 4. Lack of dedicated electromagnetic detection solutions for large lift-offs: Existing storage container testing equipment lacks a lightweight and highly sensitive integrated probe specifically designed for electromagnetic detection of large lift-offs. While permeability change detection methods are theoretically feasible, there is a lack of engineering solutions that integrate them with mature magnetic flux leakage detection technology. Summary of the Invention

[0007] To address the aforementioned problems in the existing technology, this application provides a device and method for detecting defects on the inner surface of high-strength steel.

[0008] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a high-strength steel inner surface defect detection device, including: a main control system, a composite electromagnetic detection module, and a lifting and adjustment mechanism; The main control system and the lifting adjustment mechanism are electrically connected; the lifting adjustment mechanism is mechanically connected to the composite electromagnetic detection module. The composite electromagnetic detection module includes: a magnetic flux leakage channel structure, a permeability channel structure, a mode switching and control unit, and a magnetizer; both the magnetic flux leakage channel structure and the permeability channel structure are electrically connected to the mode switching and control unit; the magnetic flux leakage channel structure and the permeability channel structure share the magnetizer; The lift-off adjustment mechanism is used to adjust the lift-off height of the magnetizer; the main control system is used to parse the detection command and determine the detection mode based on the parsing result and the lift-off height of the magnetizer; the mode switching and control unit is used to start the leakage magnetic channel structure or the permeability channel structure for detection based on the detection mode to obtain the detection signal; the main control system is also used to add a timestamp and a position stamp to the detection signal.

[0009] Secondly, this application provides a method for detecting defects on the inner surface of high-strength steel, including: Obtain the lift-off height of the magnetizer; The detection mode is determined based on the lift-off height; Based on the aforementioned detection model, defect detection is performed on the inner surface of high-strength steel, and the detection results are obtained.

[0010] According to the specific embodiments provided in this application, this application has the following technical effects: This application provides a device and method for detecting defects on the inner surface of high-strength steel. The main control system analyzes the detection commands and determines the detection mode based on the analysis results and the lift-off height of the magnetizer. The mode switching and control unit activates the leakage magnetic channel structure or the magnetic permeability channel structure for detection based on the detection mode. It can intelligently switch or integrate different detection modes according to the real-time lift-off height or preset program to ensure that reliable defect indication signals can be obtained under various working conditions (especially under large lift-off). By incorporating a magnetic flux leakage channel structure, a permeability channel structure, a mode switching and control unit, and a magnetizer within the composite electromagnetic detection module, and by sharing a magnetizer between the magnetic flux leakage channel structure and the permeability channel structure, the effective back-side defect detection magnetizer lifting range can be expanded from approximately 15mm in pure magnetic flux leakage mode to 20mm or even more than 30mm in fused mode, while reducing the magnetizer's size, weight, and attraction force. This significantly improves the sensitivity and reliability of high-strength steel container inner surface defect detection, as well as the adaptability and comprehensive evaluation capabilities of coating-free grinding detection. Furthermore, it effectively addresses issues such as the contradiction between lifting height and detection sensitivity, insufficient information dimensions, waste of hardware resources, and potential information loss, while enhancing adaptability to harsh field conditions. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the overall framework of a high-strength steel internal surface defect detection device provided in an embodiment of this application; Figure 2 This is a schematic diagram of a Hall sensor array provided in one embodiment of this application; Figure 3 This is a schematic diagram of an eddy current detection coil provided in an embodiment of this application; Figure 4 A general schematic diagram of an optimized Halbach magnetizer provided in an embodiment of this application; Figure 5 This is a schematic diagram of the internal structure of a Halbach permanent magnet array provided in an embodiment of this application; Figure 6 This is a schematic diagram of the structure of a permanent magnet box provided in an embodiment of this application; Figure 7 A schematic diagram of an overall device for detecting defects on the inner surface of high-strength steel according to an embodiment of this application; Figure 8 A schematic diagram of the internal circuit connection of a composite electromagnetic detection module provided in an embodiment of this application; Figure 9 A schematic flowchart illustrating a method for detecting defects on the inner surface of high-strength steel according to an embodiment of this application; Figure 10 This is a schematic diagram of the workflow provided for one embodiment of this application.

[0013] Figure label: 1-First magnet group, 2-Second magnet group, 3-Third magnet group, 4-Armature. Detailed Implementation

[0014] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0015] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] In one exemplary embodiment, this application provides a high-strength steel internal surface defect detection device, such as... Figure 1 As shown, the device is mainly deployed on scanning detection equipment and includes: a main control system, a composite electromagnetic detection module, and a lifting and adjustment mechanism.

[0017] The main control system and the lifting and adjusting mechanism are electrically connected. The lifting and adjusting mechanism is mechanically connected to the composite electromagnetic detection module.

[0018] The composite electromagnetic detection module includes: a magnetic flux leakage channel structure, a permeability channel structure, a mode switching and control unit, and a magnetizer. Both the magnetic flux leakage channel structure and the permeability channel structure are electrically connected to the mode switching and control unit. The magnetic flux leakage channel structure and the permeability channel structure share a common magnetizer.

[0019] The lift-off adjustment mechanism is used to adjust the lift-off height of the magnetizer. The main control system is used to parse the detection command and determine the detection mode based on the parsing results and the lift-off height of the magnetizer. The mode switching and control unit is used to activate the leakage magnetic flux channel structure or the permeability channel structure for detection based on the detection mode to obtain the detection signal. The main control system is also used to add timestamps and position stamps to the detection signal. The detection modes include leakage magnetic flux detection priority mode (i.e., mode A), permeability change detection priority mode (i.e., mode B), and fusion detection mode (i.e., mode C).

[0020] This application enables defect detection under large lifting conditions by setting up a composite electromagnetic detection module and switching logic for different detection modes executed by the main control system.

[0021] In one exemplary embodiment of this application, the detection device provided in this application can accept detection start / stop commands and mode selection commands from an external host computer (such as an industrial control computer), and transmit the detection result data back to the host computer for display.

[0022] The external host computer is part of the application environment or existing equipment of the detection device provided in this application, and does not constitute a limitation on the detection device provided in this application. Its main function is to provide a basic human-machine interface for the operator to issue macro commands to start / stop detection and to pre-set forced mode switching based on the known surface condition of the tank.

[0023] Based on the above description, in practical applications, the interaction between the detection device provided in this application and the external host computer is extremely simple, aiming to independently complete the following core detection tasks without relying on complex algorithms of the host computer: (1) Command reception: The main control system receives the preset task package sent by the external host computer. The preset task package must be very simple and may include a start scan command or a specific area forced detection mode preset by the operator (for example, the operator manually specifies the area to use the magnetic permeability change detection priority mode (i.e., mode B) based on a known area map).

[0024] (2) Data Upload and Display Assistance: The main control system only uploads the final processed defect judgment results with location coordinates (such as defect location, depth, and confidence level). The preset software in the external host computer only performs the conventional mapping from data to image, which is used to display the real-time changes of the peak-to-peak curve of the leakage magnetic signal and the impedance plane diagram of the permeability disturbance, to assist the operator in making the final qualitative confirmation of the defect.

[0025] Furthermore, the main control system, as the central hub for motion control and data aggregation, executes the following internal process: (1) Motion control and pose calculation: The detection command from the external host computer is parsed, and the drive device scans along a predetermined trajectory. At the same time, inertial navigation or odometer data is integrated to calculate the absolute position of the composite electromagnetic detection module on the surface of the object being inspected in real time, providing a precise spatial coordinate reference for defect location.

[0026] (2) Sensor integration and synchronous triggering: As a communication relay, it sends a synchronous clock signal to the composite electromagnetic detection module. In the fusion detection mode (mode C), the main control system strictly controls the timing of the Hall sensor array acquisition and the eddy current detection coil excitation to ensure that the axial component of the leakage magnetic field (Bx) and the change in coil induced voltage (ΔV) are acquired synchronously at the same spatial position, thus eliminating spatial misalignment error.

[0027] (3) Data Packaging and Streaming: Receive the detection signal (i.e. the original digital signal) from the composite electromagnetic detection module, add timestamp and location stamp, and upload it to the external host computer through the high-speed industrial bus to ensure that the massive electromagnetic detection data is not lost.

[0028] In one exemplary embodiment of this application, a composite electromagnetic detection probe is provided, which integrates a leakage magnetic field sensor and a permeability change sensor within a single compact package, sharing a magnetization field and achieving a high degree of hardware integration. Based on this, the composite electromagnetic detection module provided in this application further includes a composite probe.

[0029] The magnetic flux leakage channel structure includes: a magnetic flux leakage sensor and a first signal conditioning and acquisition circuit. The magnetic flux leakage sensor can be a Hall sensor array (such as...). Figure 2 (As shown).

[0030] The permeability channel structure includes: a permeability change sensor and a second signal conditioning and acquisition circuit. The permeability change sensor can be an eddy current detection coil (e.g., Figure 3 (As shown).

[0031] The magnetic flux leakage sensor and the first signal conditioning and acquisition circuit are electrically connected. The permeability change sensor and the second signal conditioning and acquisition circuit are electrically connected. Both the magnetic flux leakage sensor and the permeability change sensor are integrated into the composite probe. The magnetic flux leakage sensor and the permeability change sensor share a magnetizer. Both the first signal conditioning and acquisition circuit and the second signal conditioning and acquisition circuit are electrically connected to the main control system.

[0032] Based on the above description, the composite probe provided in this application is a multilayer printed circuit board on which a Hall sensor array and an eddy current detection coil are integrated to form a leakage magnetic field channel and a permeability channel.

[0033] In practical applications, a Hall sensor array is arranged with a row of high-sensitivity linear Hall elements (such as AH3503) along the scanning direction (usually laterally). It is used to directly measure the axial component (Bx) of the magnetic field leaking into the air. It operates in small lift-off mode (≤5mm).

[0034] The eddy current detection coil is positioned adjacent to the Hall sensor array or uses a coplanar design. This coil is typically an integrated excitation and reception differential coil. It is used to detect changes in coil impedance (or induced voltage) caused by variations in the relative permeability of the steel plate surface due to defects, under alternating current excitation. It operates in a large lift-off mode (greater than or equal to 10 mm). Coil parameters (such as number of turns, diameter) are determined based on the optimal excitation frequency, such as 120 kHz determined through simulation and experimentation.

[0035] In one exemplary embodiment of this application, the magnetizer used in this application may be an optimized Halbach magnetizer (such as...). Figure 4 As shown). The optimized Halbach magnetizer includes a Halbach permanent magnet array (such as...). Figure 5 (as shown) and permanent magnet box (such as Figure 6 (As shown). The Halbach permanent magnet array is set in a permanent magnet box.

[0036] like Figure 5 As shown, the Halbach permanent magnet array includes: a first magnet group 1, a second magnet group 2, a third magnet group 3, and an armature 4. The N pole of the first magnet group 1 and the S pole of the second magnet group 2 both rest on the armature 4. The third magnet group 3 is positioned between the first magnet group 1 and the second magnet group 2, with its N pole facing the first magnet group 1. The centerline of the third magnet group 3 is perpendicular to the centerline of the first magnet group 1. The centerline of the first magnet group 1 is parallel to the centerline of the second magnet group 2. The centerline refers to the connecting line between the N pole and the S pole.

[0037] The first magnet group 1 and the second magnet group 2 each consist of eight permanent magnets with dimensions of 30 mm in length, 40 mm in width, and 30 mm in height. The third magnet group 3 consists of four permanent magnets with dimensions of 60 mm in length, 40 mm in width, and 15 mm in height. All permanent magnets are installed below the armature 4, which guides the direction of magnetic flux, and together with the test piece, they form a complete magnetic flux loop.

[0038] The assembly structure of the permanent magnet box described above can further ensure the positioning accuracy and installation stability of the magnet assembly.

[0039] In one exemplary embodiment of this application, the first signal conditioning and acquisition circuit includes a power amplifier, a filter, and an analog-to-digital converter (ADC) connected in sequence. The ADC is electrically connected to the main control system. Figure 8 As shown, the second signal conditioning and acquisition circuit includes an excitation signal generator, a power amplifier, a lock-in amplifier, and an ADC channel connected in sequence. The ADC channel is electrically connected to the main control system.

[0040] Based on the aforementioned structure of the second signal conditioning and acquisition circuit, in practical applications, the signal extraction function of the detection device provided in this application follows the differential impedance balance principle. For example, the sinusoidal excitation signal generated by the signal generator drives a bridge circuit containing two symmetrical excitation coils (i.e., eddy current detection coils, or simply coils) via a power amplifier. During the scanning process, when the composite probe passes through the defect area, back-side damage causes a change in the local permeability of the material surface. This change causes a dynamic change in the equivalent impedance of the coils, thereby disrupting the original balance of the bridge. At this time, the two voltage signals input to the differential amplifier produce a slight shift in phase or amplitude. The differential voltage signal, pre-processed by the differential amplifier, is sent to a lock-in amplifier for same-frequency detection and extraction. Through this process, the voltage signal ΔV characterizing the defect can be accurately extracted from complex electromagnetic noise environments.

[0041] Among them, the lock-in amplifier is a general-purpose instrument or functional module used for weak signal detection. Its internal core functional link consists of a multiplier (phase-sensitive detector) and a low-pass filter cascaded together. Figure 8 The multiplier in the lock-in amplifier is a specific circuit unit that performs the crucial step of same-frequency detection inside the lock-in amplifier.

[0042] In one exemplary embodiment of this application, the mode switching and control unit may be based on an FPGA to control whether to enable the leakage magnetic channel structure or the permeability channel structure, or both simultaneously, and to operate in a specific timing sequence.

[0043] In one exemplary embodiment of this application, a power management module may also be provided in the detection device provided in this application to provide stable voltage to each component.

[0044] In one exemplary embodiment of this application, the magnetizer lift-off height is precisely adjusted to adapt to the magnetization distance requirements of different detection conditions, ensuring detection sensitivity and signal-to-noise ratio. The lift-off adjustment mechanism includes an adjustment screw and multiple guide shafts.

[0045] The composite electromagnetic detection module is connected to the high-strength steel body to be tested via multiple (e.g., four) guide shafts and adjusting screws. Based on this, in practical applications, a high-intensity, highly uniform vertical bias magnetic field can be formed in the region directly below the magnetizer. A 15mm lift-off is used for saturation magnetization, ensuring that the leakage magnetic field caused by defects on the back of the tested steel plate is sufficient to be detected by the Hall sensor. A 30mm lift-off is used for unsaturation magnetization, allowing the permeability disturbance caused by defects on the back of the tested steel plate to be transmitted to the upper surface of the steel plate. This design maximizes magnetization capacity within a limited volume, forming the basis for the large lift-off detection capability of the detection device provided in this application.

[0046] The 15mm setting was based on considerations from the following three levels: 1. Magnetization State Level: Ensuring the steel plate reaches saturation magnetization. A fundamental prerequisite for magnetic flux leakage detection is that the steel plate under test must reach or approach saturation magnetization, allowing the back-side defects to generate a sufficiently strong magnetic flux leakage field. For 20mm thick high-strength steel, the vertical bias magnetic field generated by the magnetizer attenuates as the lift-off value H increases. Simulation analysis and experimental verification show that when H ≤ 15mm, the magnetic field strength acting inside the steel plate is sufficient to achieve saturation magnetization; when H exceeds this value, the steel plate gradually exits the saturation region, and the magnetic flux leakage signal strength begins to decrease significantly. Therefore, H = 15mm is the critical upper limit for maintaining saturation magnetization.

[0047] 2. Signal Quality: Ensure the magnetic flux leakage signal has an acceptable signal-to-noise ratio. Even if the steel plate is not fully saturated, a weak magnetic flux leakage signal may still be generated. However, experimental data shows that when H exceeds 15mm, for a standard defect with a depth of 4mm, the peak-to-peak value Vpp of the Hall sensor output decays to a level below the preset judgment threshold Vth, and the deterioration of the signal-to-noise ratio leads to a sharp increase in the false negative rate. Therefore, H=15mm is an engineering threshold to ensure the reliability of the magnetic flux leakage detection mode.

[0048] 3. Mode Classification Level: Providing clear physical criteria for adaptive switching. 15mm and 30mm together constitute the boundary values ​​of the detection mode determination range. Below 15mm is the advantageous range for magnetic flux leakage detection, and above 30mm is the advantageous range for magnetic permeability detection, with the area in between being a transitional and fusion range. This classification enables the detection device provided in this application to automatically select the optimal detection strategy based on a real-time measurable physical quantity (H), avoiding the failure of a single method due to gradual changes in operating conditions.

[0049] In one exemplary embodiment of this application, the lifting and adjustment mechanism, as a whole, can be mounted on the base plate of the detection robot to support and adjust the composite electromagnetic detection module. It mainly consists of the following functional components: (1) Fixed base: rigidly connected to the vehicle body floor.

[0050] (2) Main lifting drive and transmission components: receive instructions from the main control system and provide large stroke driving force in the vertical direction.

[0051] (3) Guiding and support components: to ensure the smoothness and rigidity of the movement of the lifting components.

[0052] (4) Magnetizer mounting plate: As the output end of the main lifting motion, it is used to fix the magnetizer.

[0053] (5) Probe independent fine-tuning component: installed below the magnetizer mounting base plate, providing a small stroke and high-precision vertical displacement relative to the bottom surface of the magnetizer.

[0054] The magnetizer is rigidly fixed to the magnetizer mounting base plate by bolts and moves as a whole with the main lifting drive assembly. The composite probe is mounted on the probe independent fine-tuning assembly directly below the magnetizer, allowing for independent lifting and lowering relative to the bottom surface of the magnetizer. This series structure of large-stroke overall lifting and small-stroke independent fine-tuning is key to enabling differentiated settings of the magnetizer's lift-off value H and the probe's lift-off value h.

[0055] Based on the above description, the permeability change detection method provides a new approach for detecting deep defects under large lift-off conditions. This method is based on the local relative permeability perturbation of the material caused by defects under a weak bias magnetic field, enabling sensitive detection of the internal state of ferromagnetic materials. However, existing technologies have not yet provided a solution for efficiently integrating permeability change detection and leakage magnetic field detection on the same hardware platform and under the same magnetization conditions, achieving multi-physics field collaborative detection and intelligent mode switching. To address the shortcomings of existing technologies, the overall appearance of the high-strength steel internal surface defect detection device provided in this application is as follows: Figure 7 As shown. Based on the research on lightweight magnetic circuits and Halbach optimization, this application proposes a high-strength steel internal surface defect detection device that integrates leakage magnetic flux and permeability change detection. This device integrates a leakage magnetic flux sensor (Hall element array, Hall sensor array) and a permeability change sensor (eddy current detection coil) into the same composite probe, sharing an optimized Halbach magnetizer. Through intelligent signal acquisition and processing, it automatically selects or integrates the two detection modes according to actual working conditions, thereby maintaining high sensitivity and high reliability in detecting internal surface defects of high-strength steel containers within a larger lifting range (e.g., greater than 15 mm), significantly improving the adaptability and comprehensive evaluation capability of coating-free grinding inspection.

[0056] Based on the same inventive concept, this application also provides a method for detecting internal surface defects of high-strength steel, applicable to the implementation of the aforementioned high-strength steel internal surface defect detection device. The solution provided by this method is similar to the implementation described in the aforementioned device; therefore, the specific limitations in one or more embodiments of the high-strength steel internal surface defect detection method provided below can be found in the limitations of the high-strength steel internal surface defect detection device described above, and will not be repeated here.

[0057] In one exemplary embodiment, such as Figure 9 As shown, a method for detecting defects on the inner surface of high-strength steel is provided, including: Step 100: Obtain the lift-off height of the magnetizer.

[0058] Step 101: Determine the detection mode based on the lift-off height.

[0059] Step 102: Based on the detection model, detect defects on the inner surface of high-strength steel and obtain the detection results.

[0060] In an exemplary embodiment of this application, based on the implementation architecture of the above method, the specific implementation process of the high-strength steel internal surface defect detection device provided in this application will be described. For example... Figure 10 As shown, this implementation process includes: Step 1: Initialize the system (i.e., initialize the detection device).

[0061] Before the inspection begins, the inspection device first executes the initialization procedure. Based on the estimated working conditions of this inspection task (such as the coating thickness on the steel plate surface and the weld reinforcement), the external host computer sends initial parameter commands to the main control system, setting two key distance parameters: (1) Lift-off value H of the magnetizer (i.e., lift-off height, unit mm): This is the vertical distance from the bottom surface of the Halbach permanent magnet array to the surface of the steel plate, which is adjusted by the lift-off adjustment mechanism. The lift-off value H determines the distance between the bottom surface of the permanent magnet and the surface of the steel plate, and its core purpose is to control the magnetization state inside the steel plate. When the lift-off value H is small (e.g., ≤15mm), the magnetizer is close to the surface of the steel plate, and the high-intensity magnetic field generated by the Halbach permanent magnet array fully acts on the steel plate, making it reach a saturated magnetization state. In this state, defects on the back of the steel plate will cause obvious magnetic field leakage, forming a leakage magnetic field that can be detected by the Hall sensor. When the lift-off value H is large (e.g., ≥30mm), the magnetizer is far away from the steel plate, the magnetic field strength acting on the steel plate is reduced, and the steel plate is in a non-saturated bias magnetization state. In this state, although the leakage magnetic field is weak, the established DC bias field provides the necessary working conditions for the eddy current coil to detect permeability disturbances. Therefore, the setting of the lift-off value H mainly serves to control the magnetization state and indirectly determines which detection principle is applicable.

[0062] (2) Lift-off value h (unit: mm): This is the vertical distance from the bottom surface of the composite probe to the surface of the steel plate, which is usually linked to or independently fine-tuned with respect to the lift-off height of the magnetizer. The lift-off value h determines the distance between the bottom surface of the composite probe and the surface of the steel plate, and its core purpose is to control the coupling efficiency between the sensor and the signal source. The sensing intensity of the Hall sensor array for the leakage magnetic field decreases exponentially with increasing distance, so h needs to be as small as possible to capture weak leakage magnetic field signals. The eddy current detection coil is based on the principle of electromagnetic induction, and its sensing sensitivity also decreases with increasing distance. However, because of its high operating frequency (120kHz) and reliance on lock-in amplification to extract weak impedance changes, the tolerable lift-off value is relatively large. Based on this, the requirements for h are different in different detection modes: (1) Mode A requires h to be as small as possible (e.g., 3mm) so that the Hall sensor array is close to the surface of the steel plate to maximize the capture capability of the leakage magnetic field signal; (2) Mode B requires h to be slightly larger (e.g., 5mm) to ensure the sensing sensitivity of the eddy current coil while leaving a certain mechanical safety clearance.

[0063] Therefore, the setting of h mainly serves to optimize sensor sensitivity.

[0064] In practical applications, the requirements for the combination of magnetization intensity and sensor distance differ between magnetic flux leakage detection and permeability change detection. A single lift-off value cannot simultaneously meet the optimal operating conditions for both modes. Therefore, H and h need to be set separately and adjusted in conjunction with each other / independently. For example, Mode A requires a moderate H (15mm, to ensure saturation magnetization) and a very small h (3mm, to ensure the strength of the magnetic flux leakage signal). If h increases to 15mm along with H, the magnetic flux leakage signal will be significantly attenuated, making effective detection impossible. Mode B requires a larger H (30mm, to establish an unsaturated bias field) and a relatively smaller h (5mm, to ensure eddy current sensing sensitivity). If h increases to 30mm along with H, the eddy current signal will also be excessively attenuated.

[0065] Based on the above description, when the system switches between modes A / B / C according to the operating conditions, the lift-off adjustment mechanism can simultaneously adjust H, while the probe fine-tuning mechanism simultaneously adjusts h to the optimal value corresponding to that mode, achieving joint optimization of magnetization conditions and sensing distance. H determines the mechanical clearance between the magnetizer and the steel plate (i.e., obstacle-crossing capability), and h determines the clearance between the probe and the steel plate. In the large lift-off mode, H increases to meet obstacle-crossing requirements, but h can maintain a small increase to preserve eddy current sensing sensitivity as much as possible. The two work together to achieve a balance between obstacle-crossing capability and detection performance.

[0066] After the two key distance parameters are set, the main control system drives the lifting and adjustment mechanism to move the composite electromagnetic detection module to the target height and completes the zero-point calibration and gain setting of the first and second signal conditioning and acquisition circuits. During the initialization phase, a data communication link is established with the external host computer to prepare for receiving detection commands.

[0067] Step 2: Automatically determine the detection mode.

[0068] After initialization, the system enters the automatic judgment phase of the detection mode. The external host computer or main control system reads the real-time feedback of the magnetizer's lift-off H from the displacement sensor built into the lift-off adjustment mechanism, and performs mode selection based on a preset logic threshold. The specific execution process of the mode judgment logic is as follows: If H≤15mm, the current working condition is determined to be a small lift-off state. At this time, the steel plate surface is relatively clean, the magnetizer is close to the steel plate, and the bias magnetic field is sufficient to make the tested steel plate reach or approach saturation magnetization. The system automatically selects mode A and sends the instruction to the composite electromagnetic detection module.

[0069] If H ≥ 30mm, the current operating condition is determined to be a large lifting state. At this time, it may encounter thick coatings, high welds, or irremovable debris. The leakage magnetic field signal has attenuated to the noise level. The system automatically selects mode B and notifies the composite electromagnetic detection module to switch the operating state.

[0070] If 15mm < H < 30mm, the current position is determined to be in the intermediate lift-off transition range. At this point, the reliability of a single detection method is uncertain, so mode C is automatically selected, and both sensing channels are activated simultaneously for complementary verification.

[0071] Once the mode determination result is determined, the main control system sends the decision signal to the mode switching and control unit inside the composite electromagnetic detection module, triggering the corresponding hardware channel configuration.

[0072] Step 3: Execute the selected detection mode.

[0073] After receiving the corresponding mode command, the composite electromagnetic detection module controls the internal analog switches and signal paths through the mode switching and control unit to complete the hardware configuration and signal acquisition for the corresponding mode. The specific execution processes for the three AC modes are as follows: (a) The specific execution process of Mode A.

[0074] (1) Initial hardware configuration.

[0075] After the device selects mode A according to the judgment logic in step 2 above, the mode switching and control unit inside the composite electromagnetic detection module immediately executes the following hardware configuration: Turn on the power supply to the Hall sensor array to enable the preamplifier circuits and filters (anti-aliasing) of each channel to operate.

[0076] Switch the output of the excitation signal generator to the high-impedance state via an analog switch to turn off the eddy current excitation source (this operation is completed when entering mode A and is not triggered by subsequent identification results).

[0077] Configure the analog-to-digital converter (ADC) to continuously acquire data from the leakage magnetic channel (i.e., the Hall channel) at a preset sampling rate.

[0078] (2) Signal acquisition and preprocessing.

[0079] The composite probe moves along the surface of the steel plate with the testing equipment, and the Hall sensor array senses the axial component Bx of the leakage magnetic field on the back of the steel plate in real time. Since the steel plate has been saturated magnetized by the magnetizer, defects such as cracks and corrosion pits on the back will cause local magnetic lines of force to escape from the surface, forming a detectable leakage magnetic field disturbance.

[0080] The axial component Bx of the acquired leakage magnetic field is processed using the following preprocessing procedure: 1) DC blocking and amplification: The DC bias component caused by the strong magnetic field of the magnetizer itself is removed by the filter, and only the dynamic change caused by the defect is retained. The weak signal is then amplified to the full scale range of the ADC by the power amplifier.

[0081] 2) Bandpass filtering: A digital bandpass filter (passband range is usually 0.1Hz to 1kHz) is used to suppress low-frequency drift and high-frequency electromagnetic interference.

[0082] (3) Specific process of defect identification.

[0083] The preprocessed waveform data of the axial component Bx of the leakage magnetic field is fed into the defect identification algorithm in the control system. The identification process is divided into two sub-steps: feature extraction and decision-making. 1) Feature Extraction: The Bx waveform at each scanning position is analyzed in real time to extract the following quantized feature parameters: 12) Peak-to-peak value Vpp: This is the amplitude difference between the positive peak and the negative valley in the waveform. This value is approximately positively correlated with the depth and volume of the defect, and characterizes the depth and volume of the defect.

[0084] 13) Zero crossing width W: This is the spatial distance between the positive and negative crossings of the zero line of the waveform. This value reflects the opening width of the defect along the scanning direction.

[0085] 14) Waveform gradient K: the rising / falling slope of the signal within the peak-to-peak range, used to help distinguish between surface anomalies and internal defects (such as surface scratches and internal cracks).

[0086] 2) Judgment Decision: The extracted features are compared with the built-in calibration threshold Vth (determined through manual defect test plate calibration), resulting in: If Vpp ≥ Vth and W is within the effective defect width range, then a suspected back-side defect is determined to exist at the current location. Otherwise, no defect exists.

[0087] Furthermore, based on the magnitude of Vpp and the interpolation of the calibration curve, the equivalent depth d of the defect is estimated, and it is divided into three levels according to the depth range: Level I (shallow), Level II (medium), and Level III (severe).

[0088] (4) Recognition result output and subsequent actions.

[0089] The identification results include: defect marker bit (present / absent), estimated defect depth d, and defect level. This data, along with the spatial coordinates of the location, is packaged together and uploaded by the main control system to an external host computer for display and storage.

[0090] In Mode A, the shutdown state of the eddy current excitation source is a hardware configuration determined during the mode selection phase and is unrelated to the identification result. The identification result is only used for defect determination and will not trigger the dynamic activation or deactivation of the excitation source.

[0091] (ii) The specific execution process of Mode B.

[0092] (1) Initial hardware configuration.

[0093] When mode B is selected, the mode switching and control unit performs the following hardware configuration: Enable the excitation signal generator and output a sinusoidal excitation current with a frequency of 120kHz to the eddy current detection coil.

[0094] Enable the reference and signal channels of the lock-in amplifier to prepare for amplitude and phase detection of impedance changes.

[0095] Disconnect the power supply to the Hall sensor array to completely shut down the leakage magnetic channel in order to reduce power consumption (this operation is completed when entering mode B).

[0096] (2) Signal acquisition content.

[0097] When an eddy current detection coil is excited by an alternating current of 120 kHz, it generates a high-frequency alternating magnetic field that acts on the surface of a steel plate. This magnetic field induces eddy currents within the skin depth of the steel plate, and the distribution and intensity of the eddy currents are directly affected by the local relative permeability μr of the steel plate material.

[0098] When defects (such as cracks) exist on the back of the steel plate, the local stress concentration or material discontinuity in the defect area will cause a slight disturbance in the relative permeability μr at that location. Under the action of the DC bias magnetic field provided by the magnetizer, this permeability disturbance is transmitted along the thickness direction to the upper surface of the steel plate, thereby causing a change in the equivalent impedance of the eddy current coil.

[0099] The impedance change was extracted using a differential bridge circuit and then synchronously demodulated by a lock-in amplifier, ultimately yielding the following two types of data: 1) Change in induced voltage amplitude ΔV: reflects the combined change in the coil's equivalent resistance and inductive reactance.

[0100] 2) Phase offset Δ It reflects the change in the ratio of inductive reactance to resistivity caused by permeability disturbance, and is more sensitive to defect depth information.

[0101] (3) Specific process of defect identification.

[0102] The defect identification process in Mode B also includes two sub-steps: feature extraction and decision-making. 1) Feature extraction: The in-phase component (I) and quadrature component (Q) of the lock-in amplifier output are calculated to obtain: 11) Amplitude change rate RA: RA = ΔV / V0 × 100%, where V0 is the reference voltage amplitude calibrated in the defect-free area.

[0103] 12) Phase angle offset: Δ =arctan(Q / I)- ,in This is the reference phase for the defect-free region.

[0104] 2) Decision-making: Combine RA with Δ When used as two-dimensional features for joint determination, we have: If RA≥RA th (Preset amplitude change threshold) and Δ If the current position is within the preset effective phase shift range, it is determined that there is an abnormal magnetic permeability response caused by a backside defect.

[0105] Furthermore, according to Δ The numerical value and calibration curve interpolation are used to estimate the equivalent depth d of the defect. Studies show that for a 20mm thick steel plate, under 120kHz excitation, the phase shift Δ... It exhibits a monotonically increasing relationship with the defect depth.

[0106] (4) Recognition result output and subsequent actions.

[0107] The identification results include: defect marker bits, estimated defect depth, amplitude change rate, and original phase offset values. The data is uploaded to an external host computer for display.

[0108] The Hall sensor array's off state in Mode B is a preset action during the mode selection phase, not triggered by the recognition result. Even if no defects are detected during the recognition process, the Hall sensor array remains off to reduce device power consumption and avoid unnecessary electromagnetic interference.

[0109] (III) The specific execution process of Mode C.

[0110] (1) Hardware status and synchronous acquisition configuration.

[0111] When mode C is selected, the mode switching and control unit simultaneously enables the Hall sensor array signal conditioning channel and the eddy current coil excitation detection channel. To achieve spatial synchronous acquisition of the two physical field signals, the following synchronization control strategy is executed: The main control system sends a synchronous trigger pulse to the composite electromagnetic detection module. The trigger pulse is linked with the encoder output of the scanning mechanism to ensure that a data acquisition trigger is generated every fixed distance (e.g., 1 mm).

[0112] Under the same trigger pulse, the FPGA controls the ADC to synchronously sample the Bx value of the leakage magnetic channel, and simultaneously latches the I and Q component values ​​of the current output of the lock-in amplifier, thereby ensuring that the Bx signal and the ΔV signal are strictly aligned in space.

[0113] (2) The content of the collected data.

[0114] In mode C, each sampling point simultaneously obtains the following two types of raw data: 1) Magnetic leakage data: Axial component Bx (unit: mT), dynamic change value after preprocessing.

[0115] 2) Permeability data: Amplitude change ΔV (unit: mV) and phase shift Δ of the induced voltage of the eddy current coil. (Unit: °).

[0116] The two sets of data are stamped with the same timestamp and spatial location stamp, forming a bimodal data pair.

[0117] (3) The specific process of data fusion algorithm.

[0118] The purpose of the fusion algorithm is to comprehensively utilize the sensitivity of leakage magnetic field signals to geometry and the sensitivity of permeability perturbation signals to changes in the electromagnetic properties of materials, thereby improving the accuracy of defect identification and its anti-interference capability. This application adopts a feature-level fusion strategy, and the specific algorithm flow is as follows: Step 1: Single-modal feature extraction.

[0119] (1) For the Bx signal at each sampling point, calculate the statistical characteristics within its local window (usually taking 5 sampling points before and after): The leakage magnetic feature vector is FBx=[Vpp,W,K], where K is the maximum gradient.

[0120] (2) For the eddy current signal at the same sampling point, calculate its statistical characteristics within the local window: Eddy eigenvector FEddy=[RA,Δ ].

[0121] Step 2: Construction and normalization of feature vectors.

[0122] The feature vectors of the two modalities are concatenated into a joint feature vector Fjoint: Fjoint=[Vpp,W,K,RA,Δ ].

[0123] To eliminate the impact of differences in feature dimensions on subsequent classifiers, the Z-score standardization method is used to normalize each feature component, making its mean 0 and standard deviation 1. The normalization parameters (mean and standard deviation) are calculated from a pre-established calibration database.

[0124] Step 3: Classifier decision.

[0125] The normalized joint feature vector Fjoint is input into a pre-trained support vector machine (SVM) classifier (referred to as the classifier).

[0126] For example, the classifier inputs a 5-dimensional joint feature vector Fjoint. The classifier outputs: 1) Defect confidence P (a continuous value between 0 and 1), representing the probability that a true backside defect exists at the current location. 2) Defect type label (optional), such as "crack", "corrosion pit", "no defect".

[0127] The classifier training process is completed in the offline calibration stage of the system: using calibration test boards with different depths and types of defects pre-set manually, a large amount of bimodal data is collected at different lift heights, feature vectors are extracted and labeled with the true category, and the optimal classification hyperplane is obtained through training.

[0128] Step 4: The logic for determining fusion.

[0129] The final determination is made based on the defect confidence score P output by the classifier: If P ≥ Pth (a preset reliability threshold, usually 0.8), then a defect is identified. Otherwise, no defect exists.

[0130] Furthermore, the defect depth is estimated by using the regression relationship between the confidence level P and the calibration data: d=f(P), where f is the mapping function obtained by polynomial fitting.

[0131] (4) Output of fusion results.

[0132] The final output of Mode C includes: defect marker bits and confidence level P; estimated defect depth d; defect type label (e.g., identification); and raw bimodal feature data (for further manual verification by an external host computer).

[0133] (5) Relationship with Pattern A and Pattern B.

[0134] In Mode C, both the Hall sensor array and the eddy current excitation source remain continuously operational and are not shut down due to the identification result. The fused judgment result is only used for defect report generation and does not affect the hardware configuration of the current detection mode.

[0135] Step 4: Signal processing and defect determination.

[0136] This step converts the detection signal acquired by the composite electromagnetic detection module into explicit defect indication information. While the specific execution processes for signal processing and defect determination differ depending on the working mode selected in step 3, their core logic follows a unified framework of preprocessing, feature extraction, and decision output.

[0137] Step 4.1: Signal processing and defect determination in Mode A (magnetic leakage detection priority mode). For details, please refer to the description of step (I) above.

[0138] In this mode, the eddy current excitation source is turned off, and only signals from the Hall sensor array are processed.

[0139] Step 4.2, Signal processing and defect determination in Mode B (permeability change detection priority mode). The specific process can refer to the description in step (2) above.

[0140] In this mode, the Hall sensor array is turned off, and only the signals from the eddy current detection coil are processed.

[0141] 4.3 Signal processing and defect determination in Mode C (fusion detection mode). The specific process can refer to the description in step (3) above.

[0142] In this mode, the Hall sensor array and the eddy current channel work synchronously, and the dual-modal data needs to be fused to obtain a more reliable determination result.

[0143] In the actual application process, the defect type labels can be crack, corrosion pit or no defect, etc.

[0144] Step 5, Decision-making and loop.

[0145] After completing the signal processing and defect determination at the current position, according to the scanning path planning preset by the external host computer and the current detection status, execute the following decision-making and loop logic: (1) Detection completion judgment: The main control system compares the current position coordinates with the boundary coordinates of the preset scanning area in real time. If the current position has reached the end of the scanning area or has covered all the preset paths, it is determined that the detection is completed, and the process jumps to the end process. If not, it enters the continue scanning process.

[0146] (2) Continue scanning process: The main control system controls the overall device to move along the planned path to the next detection position. During the movement, the displacement sensor built in the lift adjustment mechanism continuously monitors the lift value H of the magnetizer. If the change of H crosses the preset mode switching threshold (that is, changes from H≤15mm to 15mm<H<30mm, or from 15mm<H<30mm to H≥30mm, or undergoes the opposite change), the main control system will send a new mode selection instruction to the composite electromagnetic detection module before the start of the next sampling period, and dynamically switch to the corresponding working mode (Mode A, Mode B or Mode C), so as to achieve adaptive continuous detection for different surface conditions.

[0147] When all the preset detection areas are scanned, the external host computer aggregates the defect determination data of all sampling points and automatically generates a detection report. The generated report content can include: two-dimensional / three-dimensional defect distribution maps, defect lists (including position coordinates, depth estimation values, grades / confidence levels), statistical use of detection modes and system operation logs. At this point, a single detection task is completed, and the detection device provided by this application enters the standby state.

[0148] In an exemplary embodiment of the present application, the process of the lift adjustment mechanism performing automatic adjustment embodies the mode switching idea of the present application, rather than the structure itself. Among them: (1) Mode A drive: The main control system first controls the main lifting component to act, so that the magnetizer reaches the position of H = 15 mm. Subsequently, the probe fine-tuning component is controlled to act, so that the composite probe further extends to a position h = 3 mm from the surface of the steel plate to achieve the optimal magnetic flux leakage signal acquisition distance.

[0149] (2) Mode B drive: The main control system controls the main lifting component to lift, so that the magnetizer reaches the position of H = 30 mm, realizing large lift-off obstacle crossing and non-saturated magnetization. At the same time, the probe fine-tuning component is controlled to adjust the composite probe to a position h = 5 mm from the surface of the steel plate to balance the sensitivity and safety of eddy current detection.

[0150] (3) Mode C drive: In the range of 15 mm < H < 30 mm, according to the preset linkage curve, the two components are adjusted synchronously or step by step, so that H and h are always in the optimal combination range where both sensing channels can work effectively.

[0151] Based on the above description, the lift adjustment mechanism provided by the present application cleverly utilizes the conventional two-stage adjustment mechanism of overall + fine-tuning. By endowing it with a control strategy for determining different target values of H and h according to different physical detection principles, the problem that the magnetization effect and sensing sensitivity cannot be兼顾 in multi-modal collaborative detection is solved.

[0152] In summary, compared with the prior art, the present application has at least the following advantages: 1. The present application integrates the linear Hall sensor array and the eddy current detection coil coplanarly in the same single compact package of the circuit board, and shares the bias magnetic field generated by the same optimized Halbach magnetizer to achieve a high degree of integration at the hardware level. And, by setting the mode switching and control unit to receive the timestamp and position stamp marks of the main control system, it can ensure that the axial component of the magnetic flux leakage field collected by the Hall sensor array and the change amount of the induced voltage collected by the eddy current coil are strictly aligned in space position, eliminating the spatial misalignment error during multi-physical field data fusion. And, corresponding to the disadvantage that the system is bloated due to simply juxtaposing multiple technologies, the present application shares the box body and most of the signal processing hardware, which significantly reduces the volume, weight and power consumption compared with the scheme of carrying two independent probes, and is more in line with the requirements of lightweight and compact detection equipment.

[0153] 2. This application provides an adaptive multi-mode detection strategy based on real-time lift-off feedback. When H ≤ 15mm, mode A is executed, the eddy current excitation source is turned off, and the peak-to-peak value Vpp and zero-crossing width W of the Bx signal are used for rapid defect screening. When 15mm < H < 30mm, mode C is executed, and dual-mode data are acquired simultaneously and feature-level fusion analysis is performed. When H ≥ 30mm, mode B is executed, the Hall sensor array is turned off, and the amplitude change rate RA and phase shift Δ of the eddy current coil are used. Deep defect detection is performed. To address the drawback of single detection methods being susceptible to interference from specific operating conditions, this application employs a multi-mode design. This allows the detection device to switch to or rely on another mode for auxiliary judgment when the performance of one mode deteriorates due to operating conditions (such as sudden lift-off or interference from localized strong magnetic adsorbates on the leakage magnetic signal). This reduces the risk of missed and false detections. Furthermore, it can intelligently switch or fuse signals from two detection modes based on real-time lift-off height or a preset program, ensuring reliable defect indication signals are obtained under various operating conditions (especially under high lift-off).

[0154] 3. This application provides a magnetization-sensing collaborative working mechanism adapted to large-span lift-off. Under small lift-off (H≤15mm), the magnetizer brings the steel plate to or near saturation magnetization, enhancing the detectability of leakage magnetic fields from back-side defects. Under large lift-off (H≥30mm), the magnetizer places the steel plate in an unsaturated bias magnetization state, establishing a stable DC bias field and enhancing the sensing sensitivity of high-frequency eddy currents to local permeability disturbances Δμr caused by back-side defects. Based on this, and combined with the above description, this application, while reducing the magnetizer's size, weight, and attraction force, expands the effective back-side defect detection magnetizer lifting-off range from approximately 15mm for pure leakage magnetic fields to 20mm or even more than 30mm in fused mode through dual-mode sensing and signal fusion. This significantly expands the effective detection lifting-off range and significantly improves the adaptability of the detection device to harsh field conditions.

[0155] 4. This application provides an optimized parameter scheme for eddy current detection for thick-walled steel plates with large lift-off, which explicitly sets the excitation frequency of the eddy current detection coil to around 120kHz. This frequency is the optimal solution that balances the skin depth and permeability perturbation signal transmission efficiency, ensuring that the weak Δμr perturbation caused by defects on the back side of the steel plate is effectively transmitted to the surface and sensed by the coil.

[0156] 5. This application provides a feature-level fusion algorithm for leakage magnetic field and eddy current based on joint feature vectors, which extracts the feature vector FBx=[Vpp,W,K] (peak-to-peak value, zero-crossing width, gradient) of the leakage magnetic field signal and the feature vector FEddy=[RA,Δ (Amplitude change rate and phase shift) are concatenated to form a 5-dimensional joint feature vector Fjoint. The normalized Fjoint is input into a pre-trained classifier, which outputs a defect confidence score P (a continuous value from 0 to 1). The final defect determination and depth estimation are performed based on the confidence score P to solve the problem of misjudgment caused by insufficient signal-to-noise ratio of a single physical field signal under large lift-off conditions.

[0157] 6. This application enhances the quantitative and qualitative analysis capabilities of defects. Specifically, it addresses the limitation of existing technologies that rely on a single information dimension. The fusion mode provided in this application offers signals from two different physical principles originating from the same defect. By comparing and analyzing leakage magnetic field signals (sensitive to defect geometry) and permeability change signals (sensitive to disturbances in the electromagnetic properties of the material)—two signals from the same location but based on different physical principles—the depth, size, and type of defects can be more accurately assessed, achieving more precise quantification. This, in turn, improves the accuracy and reliability of qualitative, location, and quantitative defect assessment.

[0158] 7. This application also provides intelligent adaptive detection capability, which enables the detection device to autonomously adapt to the detection conditions of different areas by automatically switching detection modes through lifting or preset programs, realizing intelligent operation of using leakage magnetic field when close and magnetic permeability when far away, thereby significantly improving the overall detection efficiency and success rate.

[0159] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0160] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A device for detecting defects on the inner surface of high-strength steel, characterized in that, include: Main control system, composite electromagnetic detection module and lifting adjustment mechanism; The main control system and the lifting adjustment mechanism are electrically connected; The lifting and adjustment mechanism is mechanically connected to the composite electromagnetic detection module; The composite electromagnetic detection module includes: a leakage magnetic field channel structure, a permeability channel structure, a mode switching and control unit, and a magnetizer. Both the magnetic flux leakage channel structure and the magnetic permeability channel structure are electrically connected to the mode switching and control unit; the magnetic flux leakage channel structure and the magnetic permeability channel structure share the magnetizer; The lift-off adjustment mechanism is used to adjust the lift-off height of the magnetizer; the main control system is used to parse the detection command and determine the detection mode based on the parsing result and the lift-off height of the magnetizer; the mode switching and control unit is used to start the leakage magnetic channel structure or the permeability channel structure for detection based on the detection mode to obtain the detection signal; the main control system is also used to add a timestamp and a position stamp to the detection signal.

2. The high-strength steel internal surface defect detection device according to claim 1, characterized in that, The composite electromagnetic detection module further includes: a composite probe; The magnetic flux leakage channel structure includes: a magnetic flux leakage sensor and a first signal conditioning and acquisition circuit; The permeability channel structure includes: a permeability variation sensor and a second signal conditioning and acquisition circuit; The magnetic flux leakage sensor and the first signal conditioning and acquisition circuit are electrically connected; the permeability change sensor and the second signal conditioning and acquisition circuit are electrically connected; the magnetic flux leakage sensor and the permeability change sensor are both integrated into the composite probe; the magnetic flux leakage sensor and the permeability change sensor share the magnetizer; the first signal conditioning and acquisition circuit and the second signal conditioning and acquisition circuit are both electrically connected to the main control system.

3. The high-strength steel internal surface defect detection device according to claim 1, characterized in that, The magnetizer is an optimized Halbach magnetizer; The optimized Halbach magnetizer includes a Halbach permanent magnet array and a permanent magnet box; the Halbach permanent magnet array is disposed in the permanent magnet box.

4. The high-strength steel internal surface defect detection device according to claim 3, characterized in that, The Halbach permanent magnet array includes: a first magnet group, a second magnet group, a third magnet group, and an armature; the N pole of the first magnet group and the S pole of the second magnet group both abut against the armature; the third magnet group is disposed between the first magnet group and the second magnet group, and the N pole of the third magnet group faces the first magnet group; the centerline of the third magnet group is perpendicular to the centerline of the first magnet group; the centerline of the first magnet group is parallel to the centerline of the second magnet group; the centerline refers to the connecting center line between the N pole and the S pole.

5. The high-strength steel internal surface defect detection device according to claim 2, characterized in that, The first signal conditioning and acquisition circuit includes a power amplifier, a filter, and an analog-to-digital converter connected in sequence; the analog-to-digital converter is electrically connected to the main control system.

6. The high-strength steel internal surface defect detection device according to claim 2, characterized in that, The second signal conditioning and acquisition circuit includes an excitation signal generator, a power amplifier, a lock-in amplifier, and an ADC channel connected in sequence; the ADC channel is electrically connected to the main control system.

7. The high-strength steel internal surface defect detection device according to claim 2, characterized in that, The leakage magnetic field sensor is a Hall sensor array.

8. The high-strength steel internal surface defect detection device according to claim 1, characterized in that, The permeability change sensor is an eddy current detection coil.

9. The high-strength steel internal surface defect detection device according to claim 1, characterized in that, The lifting and adjusting mechanism includes an adjusting screw and multiple guide shafts; The composite electromagnetic detection module is connected to the high-strength steel body to be tested through multiple guide shafts and the adjusting screw.

10. A method for detecting defects on the inner surface of high-strength steel, characterized in that, The method is applied to the high-strength steel internal surface defect detection device as described in any one of claims 1-9; the method includes: Obtain the lift-off height of the magnetizer; The detection mode is determined based on the lift-off height; Based on the detection model, defects on the inner surface of high-strength steel are detected, and the detection results are obtained.

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